Looks like the plenum area is kinda big, I would craigslist em (lots of boat guys let em freeze and crack) and get some magnum manifolds and just reverse em if you want the turbo in front. Smaller volume and they flow really good. Like mentioned by jcc lots less iron to have to heat up also. I bet a turbo would be real soggy when cold and only slightly better when hot with those things on there.
Like this, this pic is from a member on the turbo forums (not sure if there a member here or not)but its one of my a favorite designs
